A highly sensitive method for the reassessment and quantification of 239Pu in urine samples based on a 1 MV accelerator mass spectrometry system

摘要

A new and highly sensitive method for the determination of 239Pu in human urine has beendeveloped permitting the reassessment of planchets initially prepared for alpha spectrometry (AS)analysis in the context of internal dosimetry. A set of urine samples (volume: 500 mL) was spiked withknown quantities of 239Pu, ranging from 2 to 120 fg (4.6 mBq–0.3 mBq), employing 14 pg (2.05 mBq) of 242Pu as internal standard. The Pu was purified by ion-chromatography using BioRad AG1X2anion-exchange resins (Bio-Rad Laboratories Inc.). The chemical yield was determined by alphaspectrometry,being about 80%. Afterwards, the planchets so obtained were leached with diluted HNO3and the dissolved plutonium was determined by Accelerator Mass Spectrometry (AMS) at the CentroNacional de Aceleradores (CNA) in Seville, Spain. The minimum detectable activity (MDA) for theAMS measurements was determined through the study of a set of procedural blanks, giving figuresof about 0.44 fg (1 mBq) per sample. This contrasts with the MDA obtained by AS for the same set ofsamples, of about 50 fg (0.1 mBq). The results now presented helps to demonstrate that theroutine measurement of 239Pu at ultra trace levels in human urine samples is possible with thenew-generation of compact AMS systems, offering a highly sensitive method for the reassessing ofplanchets prepared for bioassay purposes.